The genes for the Escherichia coli ribosomal proteins (r-proteins) are organized into at least 11 different transcription units. These genes, and the genes for ribosomal RNA, are expressed coordinately during cell growth. The molecular mechanisms for the balanced synthesis of these ribosomal components, and the possible interactions with the other components of the transcription and translation machinery will be investigated. To identify the regulatory elements responsible for this coordination, the effects of increased copies of specific r-protein genes will be studied. Various fragments of E. coli chromosomal DNA carrying one or several genes for r-proteins will be cloned on plasmids whose copy number can be manipulated. The effects of gene dosage will then be analyzed by correlating the number of gene copies with the (direct) effect on the synthesis of the products of the cloned genes, and the (indirect) effects on the synthesis of other r-proteins, rRNA, translation factors, and RNA polymerase subunits. In addition, the consequences of excessive gene dosage on cell viability will be determined. The analysis of a series of different strains carrying increased copies of various r-protein genes and/or regulatory sequences should permit the "dissection" of the regulatory network coordinating the synthesis of r-proteins.